Lack of significant long-term effect of dietary carbohydrates on hepatic glucose-6-phosphatase expression in rainbow trout (Oncorhynchus mykiss)

Hepatic glucose-6-phosphatase (G6Pase) plays an important role in glucose m etabolism because it catalyzes the release of glucose to the circulatory sy stem in the processes of glycogenolysis and gluconeogenesis. The present st udy was initiated to analyze the regulation of hepatic G6Pase expression by dietary carbohydrates in rainbow trout. The first step in our study was th e identification of a partial G6Pase cDNA in rainbow trout that was highly homologous to that of mammals. Hepatic G6Pase activities and mRNA levels we re measured in trout fed one of the experimental diets, with or without car bohydrates. We found no significant effect of intake of dietary carbohydrat es on G6Pase Expression (mRNA and activity) 6 hours and 24 hours after feed ing. These results suggest that there is no control of G6Pase synthesis by dietary carbohydrates in rainbow trout and that the lack of regulation of g luconeogenesis by dietary carbohydrates could at least partially explain th e postprandial hyperglycemia and the low dietary glucose utilization observ ed in this species. (J. Nutr. Biochem. 11:22-29, 2000) (C) Elsevier Science Inc. 2000. All rights reserved.